A man has been arrested on suspicion of causing a coach to overturn on a motorway, according to police.
The Oxford Tube coach carrying the driver and 12 passengers was travelling southbound on the M40, between junctions 3 and 2, at 2am when it overturned.
One passenger was taken to Wexham Park Hospital in Slough with a possible back injury.
A police spokesman said it was expected he will be released from hospital later.
The spokesman added: "Shortly after the incident, officers arrested a man nearby, who had left the scene.
"It is believed he may have had some involvement in the cause of the collision.
"The man, who is 21-years-old and from Oxford, remains in police custody.
"Two lanes of the motorway were closed until around 9.45am to allow officers to begin their investigation and for the vehicle to be recovered."